This invention relates to an air-compresing reciprocating piston-equipped internal combustion engine comprising
at least one piston having a piston head with a frontal face and a cavity, in the frontal face, which cavity has a central cavity axis, is of axially symmetrical shape, and serves as a combustion chamber;
a fuel injection nozzle having at least three orifices and being traversed by a longitudinal nozzle axis substantially intersecting the central cavity axis and encloses an accute angle therewith; and
an air-feeding unit adapted for introducing into the cavity an air charge and generating an air flow thereof in rotary motion;
each of the nozzle orifices having a central orifice axis extending therethrough and intersecting all other orifice axes in a common central point of intersection inside the nozzle, the combustion chamber-constituting cavity being divisable into a number of partial volumes or imaginary compartments allocable each to one of the fuel jets.
For reasons of construction, it is practically unavoidable that the said fuel injection nozzle is mounted with its nozzle axis in an oblique position relative to the central cavity axis, and this geometrical arrangement results in the individual orifice of the said nozzle having different through-flow coefficients relative to the nozzle axis, so that the quantities of fuel emitted by the different orifices present all differ from one another during an injection.
It is known so to arrange the orifices that the angles which their respective orifice axes enclose with the longitudinal nozzle axis are all of the same size, i.e. the angles between adjacent pairs of the different nozzle axes are also equal. In another known construction, the angles enclosed between every two orifice axes of adjacent orifices in the nozzle tip are of different sizes, however arcs of equal size are provided between the impingement points of these nozzle axes with the wall of the combustion chamber-constituting cavity. It has now been found that in these two known cases it is not possible to achieve an optimal preparation of the air-fuel mixture in the combustion chamber. Moreover, the fuel jets emerging from the individual nozzle orifices, which, for reasons of manufacture usually form the generatrices of a common cone whose apex is located on the longitudinal nozzle axis, impinge at different levels on the wall of the combustion chamber. This leads to an imperfect preparation of the air-fuel mixture and thus affects in a negative way the emission of smoke and off-gases as well as the consumption of fuel by the engine. Furthermore, this also causes an unfavorable uneven thermic load exerted on the piston.
It is further known from German Offenlegungsschrift No. 9 55 084 to allocate to each fuel jet emitted by the fuel injection nozzle a partial volume or compartment of the cavity serving as combustion chamber, all compartments thus allocated being of equal volume, which means that the total volume of the combustion chamber is divided by the number of fuel jets injected thereinto. In the case of a nozzle having four fuel jets, exactly one-fourth of the cavity volume is allocated to each of the jets. However, this measure will not permit either the obtainment of an optimal fuel-air mixture, because it does not take into account the fact that differing amounts of fuel are ejected from the individual orifices for the reasons explained hereinbefore.